See if fjalar_main.c can detect code with -fpstack-clash-protection

[markro49]

Currently we document using -fno-stack-clash-protection and have modified kvasir-tests/Makefile.common to do so. (codespecs/daikon@371f8e4)

It would be better to detect this tiny code loop in the function prologue and deal with it automatically.

On Ubuntu 20.04 system: Test case is kvasir-tests/perl, function is Perl_magic_get()